Chopper assemblies for sugar cane harvesters include a pair of counter-rotating gear-driven chopper shafts carrying opposed and overlapping blades which cooperate to cut the elongate sugar cane stalks into shorter billets.
As wear of the blades inevitably occurs, the clearance between the opposed and overlapping counter-rotating blades increases and cutting efficiency is lost.
It is known to provide means for selectively allowing rotation of one of the chopper shafts relative to its gear so that the chopper shaft can be rotated to thereby close the clearance between the overlapping blades. In this known system these means are contained within the gearbox. Therefore, making an adjustment is a difficult exercise which also risks the introduction of contaminants to the gearbox.